Documentation: clarify/correct a few sparsity related statements

Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Victoria Dye <vdye@github.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: newren

Documentation/git-clone.txt

@@ -167,10 +167,10 @@ objects from the source repository into a pack in the cloned repository.
 	configuration variables are created.
 
 --sparse::
-	Initialize the sparse-checkout file so the working
-	directory starts with only the files in the root
-	of the repository. The sparse-checkout file can be
-	modified to grow the working directory as needed.
+	Employ a sparse-checkout, with only files in the toplevel
+	directory initially being present.  The
+	linkgit:git-sparse-checkout[1] command can be used to grow the
+	working directory as needed.
 
 --filter=<filter-spec>::
 	Use the partial clone feature and request that the server sends

Documentation/git-sparse-checkout.txt

@@ -121,7 +121,7 @@ SPARSE CHECKOUT
 It uses the skip-worktree bit (see linkgit:git-update-index[1]) to tell
 Git whether a file in the working directory is worth looking at. If
 the skip-worktree bit is set, then the file is ignored in the working
-directory. Git will not populate the contents of those files, which
+directory. Git will avoid populating the contents of those files, which
 makes a sparse checkout helpful when working in a repository with many
 files, but only a few are important to the current user.